In the automotive industry, dirt adhering on the tires poses a problem in the sense that the weight of the vehicle, the air resistance and the consumption of fuel are non-negligibly increased. Furthermore, in order to ensure an optimum safety level (efficient grip) and for aesthetic reasons (especially on the lettering of the tire), there is a need for removing the dirt (mud, small stones, . . . ) from the tires prior to a new ride.
Similarly, in the aerospace industry, dirt adhering to airplane tires must be washed away before the machine is allowed to start again. Another major problem in this field is that airplane tires accumulate considerable amounts of water during take-off and flight. At the low temperatures that are experienced in high altitudes, the water turns into the state of ice during flight. Consequently, in order to remove this ice after landing, a large amount of anti-icing products must be used, involving considerable time and labor.
Furthermore, it is well understood that tires of all kinds should be as water-repellent as possible in order to optimize water evacuation and minimize the risk of aquaplaning.
Efforts to reduce air resistance of objects in motion in order to achieve a reduction in fuel consumption have been disclosed for surfaces such as the metallic surface of an airplane. For example, U.S. Pat. No. 4,865,271 by Savill teaches to provide an aerodynamic or hydrodynamic surface with so-called “riblets” for reducing drag by modification of the turbulent boundary layer (this is the thin layer of air molecules that touches the surface of the object and causes friction). The riblets comprise flow-aligned elongate projections of small height.
U.S. Pat. No. 4,706,910 by Walsh et al. discloses a system of flow control devices which result in reduced skin friction on aerodynamic surfaces. The devices cause a breakup of large-scale disturbances in the boundary layer of the flow field by the use of longitudinal striations forming vee-shaped grooves.
Against this background, it is an object of the present invention to provide rubber tires having an improved dirt-repellence, whereby the weight of the tire and the air resistance, are reduced, and savings in fuel consumption are achieved.
It is another object of the invention to provide tires having a self-cleaning effect, thus improving their optical appearance and lowering the quantity of cleaning material that is required.
It is still another object of the invention to provide tires with improved water-repellence, whereby the risk of aquaplaning is reduced. In the special case of airplane tires less anti-icing products will further be required.
Still another object of the invention is to provide tires in which color shade special effects can be incorporated without having to use colors.